Device for mechanical recording



July 11, 1944. A. CRAMWINCKEL ETI'AL 2,353,547

DEVICE FOR MECHANICAL RECORDING Filed Jan. 16, 1941 Patented July 11,944

UNITED, STATES PATENT orrlcs 1 yua a sfffc fl fmfiwfamg pel, lindhovemhAlien Property Custodian Application January II In Germany 1041, SerialJune I No. sum a. 103s 1 Claim. (01. 214-411 Our invention relates to amethod and device for mechanically recording a sound track which ticlesof film material, or the like. is largely responsible for a hiss duringreproduction. It has been suggested to remove this ,dirt from bothsurfaces of the carrier at the area of the sound track before the soundtrack is optically scanned. It is also known that a deposit of dust onthe lightsensitive emulsion prior to or during the formation of thephotographic sound track deleteriously affects the recording and thequality of the track, obtained and therefore the recording andsubsequent development and fixation are usually carried out in roomswhich are as free as possible from dust.

In photographic sound-recording it is primarily the emulsion surface, ofthe carrier, 1. e. the

surface on which recording is effected, which should be kept free fromany dirt which might intercept ordifluse the exposure light. Any dirtthat may what on the surface of the carrier remote from the exposurelight, l. e. the exposed surface of the Celluloid or acetyi cellulosesupporting layer, has no influence during the photographical recordingupon the quality of. the

sound record. During the reproduction only the particles of dirt whichexist at the area of the track have an influence and these particles areresponsible, for only a small portion of the total Although inphotographic recording it is mainly desirable to remove thelight-absorbing or light-diif-using dirt from the recording surface ofthe carrier, we have found that in mechanical recording of theabove-mentionedtype it is mainly desirable to remove bothlight-transmitting and opaque dirt from the supporting surface of' thecarrier prior to the formation of the sound track More particularly, ifonly one surface of a carrier is cleaned and the carrier is wound on areel. the cleaned surface would engage the other surface, and as thedirt would be attracted to the cleaned surface due to an electrostaticcharge on the carrier. Thus, it would be neces sary that cleaning beeflected during the recording process i. 0. after the carrier is unwoundfrom the reel and immediately before recording.

We have found that the presence of dirt on the supporting surface of thecarrier results in greatly interfering additional noise duringreproduction of a mechanically-recorded track of the above-mentionedtype. because a particle of dirt between the carrier and the supp rtinmb r causes a locally-raised position of the carrier. Thus, during therecording the cutting edge of the cutting tool penetrates locally to agreater depth into the carrier and consequently a supplementary widthvariation occurs oppositethe particle of dirt.

Our invention is of particular importance-in connection with methods ofrecording in which the width variations of the track are an enlargementof the depth variation, for instance recording of the type described inthe U. 5. Patent #1,919,116 to James A. Miller. In such methods ofrecording the amplitude of the width deformation caused by the presenceof a particle of dirt between the supporting surface of the carrier andthe surface of the supporting member :vouid be several times thethickness of the par,

icle.

If, 'in accordance with the above mentioned I patent, the track is cutby means of a cutting tool having a V-shaped cutting edgeof a largeapical angle, for instance 174 degrees, a particle of dirt having a sizeof about 20 microns may cause a local track widening of about 800microns or 0.8 mm., which in the case of a neutral, track width of 0.3mm. causes a decided local widening of the track which is audible duringreproduc tion as an intense dull detonation. Because of width variationswhich are greatly enlarged with respect to the depth variations, theinterfering influence of the presence of dirt in mechanical recording ismuch greater than in photographic recording. In fact in photographicrecording, particles of dirt between the carrier and its support are ofpractically noimportance, i. e. the locally-raised position of thecarrier causes substantially no variations in the shape of the lightline in the emulsion. If particles of dirt are present in the path ofthe recording light, the interfering influence, insofar as they mayintercept the light, depends only on their direct size.

We prefer to clean not only the supporting surface of the carrier butalso to clean the recording surface prior to the recording because oncethe track has been out it is exceedingly difflcult to remove any dirtthat gets into the depressions of the track.

During mechanical recording of the track particles. of the carrierdisengage from the chips cut therefrom and these particles may depositon both surfaces of the carrier and be pressed into the material of thecarrier during the winding operation effected subsequent to recording.Because of this we prefer also to clean the carrier on both sides afterthe recording and in some cases even again before the winding operation.

We prefer to effect the cleaning by means of a cleaning devicecomprising a group of directed hairs, for example a strip of velvet or abrush. In this case the dirt slides between some of the said hairs andis retained, so that the cleaning device is capable of absorbingconsiderable dirt before being saturated.

If the carrier has been cleaned in the manner described above, any dirtthat exists on the carrier andin some cases in the recording device isprevented from depositing on the carrier dur ing mechanical recordingand re-winding. If the sound track is optically reproduced after themechanic'al recording, it is advisable to subject the the boundary ofthe track due to the particle II will be about times the thickness ofthis particle.

It should be noted that the above diiliculties occur not only .when thetrack is surrounded by opaque portions. as shown, but also when thetrack is cut into a transparent layer and is then blackened. In thelatter case the deformation causes a sharp projection of the blackenedtrack.

The recording device diagrammatically shown in Figure 2 is used forrecording a variabledepth and variable-width sound track in a carrier ortape 21, which may be of the type shown in Fig.1. Ilf'he carrier -21 isunwound from an unwinding reel II and moves in the direction indicatedby thearrows. More particularly, the carrier 21 passes over a guideroller ll. through a cleaning device ll, over a guide roller ll, over arecording roller 20, through a cleaning device 22, through an opticalscanning system 23, over a roller Ill and onto a winding reel 24. Aroller ll presses the carrier against roller 20.

carrier to another cleaning operation prior to v the opticalreproduction in order to remove any dirt which may be deposited on thecarrier during its passage along the guide rollers and guide surfaces.

In order that the invention may be clearly understood and readilycarried into effect we shall describe the same in more detail withreference to the accompanying drawing. in which Fig. l is a perspectiveview of a carrier and shows a cutting tool,

Jig. 2 is a diagrammatic view of a recording system comprising aplurality of cleaning de- :g. 3 is a partly-sectionized side view of acleaning device, and

Hg. 4 is a side view of a cleaning device according to anotherembodiment of the invenflan.

me carrier shown in Fig. 1 comprises a thin covering layer ll of Opaquematerial provided on a supporting layer H of a transparent material ofgood cutting properties. The carrier is moved at a constant speed in thedirection of the arrow 2 over a supporting member H, which may be astationary block as shown. or s. rotating roller as shown for example at2| in Fig. 2, while a cutting tool i2 is vibrated in the direction ofthe double-headed arrow I in accordance with the sound being recorded.The cutting tool II, which has a V-shaped cutting edge having alargeapical angle, for instance an angle of about 174', removes portionsof the opaque layer II and of the cutting layer II to form in thecarrier a sound track I having depth variations and width variationswhich are an enlargement of the depth variations.

If there is a particle of dirt IS on the supporting surface of thecarrier, 1. e. the surface which bears upon the surface of thesupporting member ll. the carrier will be slightly raised locally fromthe surface of member I. As a result the thin covering layer l0 will beraised at this point and the sound track at the location of the particleII will have a width greater than that which corresponds to theampiitude of the cutting tool. With a V-shaped The recording is effectedat roller 20 by means of a recorder 2| which may have cutting tool ofthe type shown in Fig. 1. As suitable recording devices, scanningdevices and driving devices are well known in the art, furtherdescription or illustration of the same is believed to be unnecessary.

When carriers of non-conductive substance, such as carriers comprising agelatin cutting layer superimposed on a Celluloid supporting layer, areunwound from an unwinding reel in a dry atmosphere, they receive anelectrostatic charge which attracts many particles of dirt. Furthermore,dirt is deposited on the carrier at points at which the carrier isguided through the recording mechanism and at which the edges pass alongflanges or plates. 1. e. along the rollers i0 and I8. To remove thisdirt the cleaning device I! is arranged in front of the point ofrecording i. e. so as to clean the carrier before the track is cut. Asthe electric charges also exist on the carrier after cleaning andbecause of other factors causing deposition of dirt on the carrier, forexample at the guiding points, this cleaning operation should beeffected immediately prior to the recording of the track. The cleaningdevice I! therefore is arranged as close as is constructionally possiblein front of the recording device 2|. Because of the lack of space it isnot possible to locate cleaning device I! between the last guide rollerII and the recording roller 20, and this is why it is arranged after thenext to the last roller IS.

The cleaning device I! cleans not only the supporting surface but alsothe recording surface of the carrier because the particles of dirtexisting on the latter surface might enter the depressions of the cuttrack and influence the light during reproduction. Furthermore, itsshould be noted that due to the varying depth of the track it lwould .bevery diillcult to remove such paric es.

During cutting, the material removed is in the form of a continuous chipor shaving which is generally removed from the point of recording byauction. However, in practice small particles are disengaged from thisshaving and might deposit on the carrier even after cutting. There isthe danger that such particles, if they get between the carrier and thesurface of the supporting member, or during winding between the turn ofthe coil, may be pressed into the material of the terrier. Because ofthis we prefer to repeat the cleaning as soon as possible after therecording.

In the recording device of Fig. 2 the second cleaning member 22 islocated after the recording roller 20 and the roller ll, and cleans bothsurfaces of the carrier. before the opticc-electrical reproduction "forchecking the recorded sound track is effected by means of the device 23,the carrier is made as free from dirt as possible on both surfaces. Thecleaning member 21 is therefore arranged in front of the point ofoptical scanning device 21. When the carrier is then wound on thewinding reel 24 there is as little dirt as possible between the turns.If desired, cleaning my be affected again immediately beforewinding, i.e. by a cleaning device (not shown) located between reel 24 and roller5..

We may further clean the carrier when it is rewound on the unwindingreel I, which is generally of an interchangeable form. This cleaningoperation is effected by a cleaning device 2! in the rewinding path(indicated by a dotted line) of the carrier in which path the carrierengages a guide roller 2!. This cleaning operation may be effected onboth sides of the carrier or on the supporting surface.

The cleaning devices I1, 22 and I! of Fig. 2 may be of the constructionillustrated in Fig. 3. The device shown in Figure 3 comprises a housingll provided at its ends with two openings '2 and SI for the passage ofthe carrier 21, which moves in the direction of the arrow 36. Withinhousing Si and bearing upon the upper surface of the carrier 11 is apiece of velvet I while a second piece of velvet 35 engages the lowersurface of the carrier and is pressed thereto by a pressing block I! andtwo compression springs 32. The short. grouped hairs of the velvet u and3!, which extend substantially perpendicular to the surface of thecarrier brush away the particles of dirt loosely-seated on the surfacesof the carrier. The width of the said strips is greater than the widthof the carrier itself so that also the lateral sides of the latter arecleaned by the hairs.

If this brushing action is not suillcient to remove the dirt, forexample because the adhesion of the dirt to the carrier is greater thanthe force that the hairs can exert on these particles of dirt, theadhesion of the cleanin member may be increased artificially by theaddition of substances of greater adhesion, such as liquids and in somecases tacky or greasy liquids or greasy substances in general. Asexamples of such substances we may mention sulfonated resinousoil orolive oil. For this purposepa feed tube 30 extends through an aperture31 provided in the top of housing II near the point at which the carrier21 enters the cleaning device. The aperture 31 extends at leastthroughout the width of the carrier and a small supply of the desiredliquid or fat is passed through the tube 38 to the velvet and thesurface to be cleaned. The substance applied is removed together withthe dirt by the portions of the velvet strips remote from the aperture81.

If cleaning is eifected by means of a volatile Thus, we ensure thatliquid such as carbon tetrachloride with some alcohol and water, therecording surface of the' carrier may also be treated in the abovemanner. The portion of liquid which is not removed in the further partof the cleaning members volatilizes from the track. Non-volatile liquidsand fats can be used for cleaning only the supporting surface of thecarrier but they have to be removed together with the dirt by means of astrip of velvet.

The cleaning member shown in Fig. 4, which preferably serves for drycleaning, comprises four brushes I supported in carriers II. Thebristles of brushes ll are not at a right angle to the surface of thecarrier 21, as in the case of the hairs of the velvet in Fig. 3, butfrom an acute angle therewith. Furthermore, the bristles are in"anti-direction with the direction of movement 36 of the carrier 21 i.e. they form an obtuse angle with the surface of the incoming carrier.The length of the bristles is of the order of magnitude of 10 mms. i. e.many times greater than that of the velvet, and therefore each bristleper se must be stiff in order that it may form an angle with the surfaceof the carrier in spite of the pressure of the bristles on the carrier,i. e. in order that it may not become located in the plane of thecarrier. The necessary pressure of the bristles on the surface of 'thecarrier is procured by the resilience of the skilled in the art.

What we claim is: I

In a device for mechanically recording on a carrier a sound track havingdepth variations and enlarged optically-reproducible width variations,an unwinding reel for the carrier, means for recording the trackdisposed at a recording point, and means for removin dirt from thesupporting and recording surface of the carrier at a point between theunwinding reel and the recording means, comprising a housing provided atits ends with openings through which the carrier passes, a brush membersupported by one inner surface of said housing and comprising aplurality of hairs directed towards one surface of the carrier, a secondbrush member supported by a movable element of said housing andcomprising a plurality of hairs directed towards the other surface ofthe carrier, resilient means interposed between said element and asecond inner surface of the housing for urging the hairs of said latterbrushing member towards the carrier, a source of adhesive cleaning fluidand means for supplying said cleaning fluid to said brushing membersandfor maintaining selected portions thereof substantially saturated.

ARNAUD CRAMWINCKEL. CORNELIB J OHANNES DIPPEL.

